We don't know who started the argument here, but based on the video the man who initiated the physicality was the one who got the worst of it.
The National Football League's season hasn't even started yet but we already have our first fan altercation, one that took play during a scrimmage held by the Tennessee Titans. Seeing as this was a scrimmage it seems fair to assume that both men are fans of the same team, making this fight between fans seem even more ridiculous than your usual affair.
The man in the white shirt was the first to get physical when he pushed the man black/grey shirt, but that resulted in the man in the black shirt throwing a punch that left the first man a bloody mess.
Here's a video that one person captured of the altercation.